The therapeutic use of stem cells depends on the availability of pluripotent cells that are not limited by technical, ethical or immunological considerations. The goal of this proposal is to develop and bank safe and well-characterized patient-specific pluripotent stem cell lines that can be used to study and potentially ameliorate human diseases. Several groups, including ours have recently shown that adult skin cells can be reprogrammed in the laboratory to create new cells that behave like embryonic stem cells. These new cells, known as induced pluripotent stem (iPS) cells should have the potential to develop into any cell type or tissue type in the body. Importantly, the generation of these cells does not require human embryos or human eggs. Since these cells can be derived directly from patients, they will be genetically identical to the patient, and cannot be rejected by the immune system. This concept opens the door to the generation of patient-specific stem cell lines with unlimited differentiation potential. While the current iPS cell technology enables us now to generate patient-specific stem cells, this technology has not yet been applied to derive disease-specific human stem cell lines for laboratory study. Importantly, these new cells are also not yet suitable for use in transplantation medicine. For example, the current method to make these cells uses retroviruses and genes that could generate tumors or other undesirable mutations in cells derived from iPS cells. Thus, in this proposal, we aim to improve the iPS cell reprogramming method, to make these cells safer for future use in transplant medicine. We will also generate a large number of iPS lines of different genetic or disease backgrounds, to allow us to characterize these cells for function and as targets to study new therapeutic approaches for various diseases. Lastly, we will establish protocols that would allow the preparation of these types of cells for clinical use by physicians investigating new stem cell-based therapies in a wide variety of diseases.

Statement of Benefit to California:

Several groups, including ours have recently shown that adult skin cells can be reprogrammed in the laboratory to create new cells that behave like embryonic stem cells. These new cells, known as induced pluripotent stem (iPS) cells should have, similar to embryonic stem cells, the potential to develop into any cell type or tissue type in the body. This new technology holds great promise for patient-specific stem-cell based therapies, the production of in vitro models for human disease, and is thought to provide the opportunity to perform experiments in human cells that were not previously possible, such as screening for compounds that inhibit or reverse disease progression. The advantage of using iPS cells for transplantation medicine would be that the patient’s own cells would be reprogrammed to an embryonic stem cell state and therefore, when transplanted back into the patient, the cells would not be attacked and destroyed by the body's immune system. Importantly, these new cells are not yet suitable for use in transplantation medicine or studies of human diseases, as their derivation results in permanent genetic changes, and their differentiation potential has not been fully studied. The goal of this proposal is to develop and bank genetically unmodified and well-characterized iPS cell lines of different genetic or disease backgrounds that can be used to characterize these cells for function and as targets to study new therapeutic approaches for various human diseases. We will establish protocols that would allow the preparation of these types of cells for clinical use by physicians investigating new stem cell-based therapies in a wide variety of diseases. Taken together, this would be beneficial to the people of California as tens of millions of Americans suffer from diseases and injuries that could benefit from such research. Californians will also benefit greatly as these studies should speed the transition of iPS cells to clinical use, allowing faster development of stem cell-based therapies.

Progress Report:

Year 1

The goal of this project is to develop and bank safe, well-characterized pluripotent stem cell lines that can be used to study and potentially ameliorate human diseases, and that are not limited by technical, ethical or immunological considerations. To that end, we proposed to establish protocols for generation of human induced pluripotent stem cells (hiPSC) that would not involve viral vector integration, and that would be compatible with Good Manufacturing Processes (GMP) standards. To establish baseline characteristics of hiPSCs, we performed a complete molecular characterization of all existing hiPSCs in comparison to human embryonic stem cells (hESCs). We found that all hiPSC lines created to date, regardless of the method by which they were reprogrammed, shared a common gene expression signature, distinct from that of hESCs. The functional role of this gene expression signature is still unclear, but any lines that are generated under the guise of this grant will be subjected to a similar analysis to set the framework by which these new lines are functionally characterized. Our efforts to develop new strategies for the production of safe iPS cells have yielded many new cell lines generated by various techniques, all of which are safer than the standard retroviral protocol. We are currently expanding many of the hiPSCs lines generated and will soon demonstrate whether their gene expression profile, differentiation capability, and genomic stability make them suitable for banking in our iPSC core facility. Once fully characterized, these cells will be available from our bank for other investigators.
For hiPSC technology to be useful clinically, the procedures to derive these cells must be robust enough that iPSC can be obtained from the majority of donors. To determine the versatility of generation of iPS cells, we have now derived hiPSCs from commercially obtained fibroblasts derived from people of different ages (newborn through 66 years old) as well as from different races (Caucasian and mixed race). We are currently evaluating medium preparations that will be suitable for GMP-level use. Future work will ascertain the best current system for obtaining hiPSC, and establish GMP-compliant methodologies.

Year 2

The goal of this project is to develop and bank safe, well-characterized pluripotent stem cell lines that can be used to study and potentially ameliorate human diseases. To speed this process, we are taking approaches that are not limited by technical, ethical or immunological considerations. We are establishing protocols for generation of human induced pluripotent stem cells (hiPSCs) that would not involve viral vector integration, and that are compatible with Good Manufacturing Practices (GMP) standards. Our efforts to develop new strategies for the production of safe hiPSC have yielded many new cell lines generated by various techniques. We are characterizing these lines molecularly, and have found hiPSCs can be made that are nearly indistinguishable from human embryonic stem cells (hESC). We have also recently found in all the hiPSCs generated from female fibroblasts, none reactivated the X chromosome. This finding has opened a new frontier in the study and potential treatment of X-linked diseases. We are currently optimizing protocols to generate hiPSC lines that are derived, reprogrammed and differentiated in the absence of animal cell products, and preparing detailed standard operating procedures that will ready this technology for clinical utility.

Year 3

This project was designed to generate protocols whereby human induced pluripotent stem cells could be generated in a manner consistent with use in clinical trials. This required optimization of protocols and generation of standard operating procedures such that animal products were not involved in generation and growth of the cells. We have successfully identified such a protocol as a resource to facilitate widespread adoption of these practices.